The present invention relates to diagnostic medical devices. More particularly, the present invention relates to portable cardiac monitoring devices.
Through a combination of physiology, diet, and life-style factors, millions of people, just in the United States alone, have or will have some form of cardiovascular condition or disease. For many people, unfortunately, early symptoms of cardiovascular conditions are not obvious or even necessarily present. By the time the condition is apparent, it is often already at an advanced stage. At this point, therapeutic treatment options are limited, and such options are likely to carry considerable risks and costs. Early and accurate diagnosis is therefore critical to treat and stop further advance of cardiovascular conditions.
To this end, patients experiencing possible symptoms are encouraged to notify and be examined by health care professionals. Unfortunately, it may not be possible to accurately diagnose a possible condition if symptoms are generic or not present during examination. Alternatively, after a patient has been diagnosed and treatment decided, the patient's response to the treatment may need to be monitored so as to determine effectiveness and/or to fine-tune the treatment.
However, it is not practical for a health care professional to constantly monitor a patient for a set period of time, nor for a patient to stay at a clinic (or other locations with health care professionals) for a set period of time, merely for purposes of observing possible symptoms or responses. Instead, ambulatory patients are encouraged to be connected to a monitoring device for a set period of time while going about their regular routine.
An example of such a device is a Holter recorder that records cardiac signals of an ambulatory patient for a period of time, such as 24-72 hours. Holter recorders are typically configured to provide heart activity information, and in particular, electrocardiogram (ECG) recordings over a relatively long period of time. Such recordings permit identification of infrequent and transient disturbances of cardiac rhythm, which may aid in diagnosing patients with vague or intermittent symptoms such as dizziness, blackouts, or fainting spells. Such recordings may also quantify and pinpoint times and/or activities associated with a patient's infrequent symptoms. A physician may be interested not only in the unusual ECG events but also the background rhythm, which may comprise slower or overall responses to influences such as drug treatment, surgery, an implant, or stress. Moreover, a take-home diagnostic device provides more accurate and meaningful ECG recordings since the ambulatory patient is at a home setting (e.g., a natural or real setting) as opposed to an artificial setting (e.g. a doctor's office).
Effectiveness of ECG recording devices involve not only how well cardiovascular signals are measured and recorded, but also its ease of use and cost-effectiveness. Typical Holter recorders, unfortunately, are not inexpensive. Use of diagnostic devices, especially take home diagnostic devices, are also cost-effective and most beneficial for the end-customer (i.e., patients), but may in fact be more costly for medical practitioners due to device purchase and maintenance costs and loss of revenue from future appointments from a given patient. For clinics with budget constraints, spending thousands of dollars for each Holter recorder can be prohibitive.
Ease of use of typical Holter recorders is problematic. The electrode assemblies in typical ambulatory records are reused for many patients, sometimes up to several hundred patients per assembly. The electrode assemblies are not sterilized between uses. Patients can find the idea of having to wear such cables on their skin for up to several days to be unpleasant.
Typical Holter recorders also tend to be large and thus cumbersome for a patient to carry around at all times during the recording period. And even with the large size, typical Holter recorders can be inefficient in power consumption, which further requires use of large batteries.
Due to ease of use issues, it is not uncommon for patients to prematurely end the recording period. Alternatively, patients may be reluctant to even commit to the monitoring because of the degree of discomfort and interference with everyday activities.
Thus, there is a need for a small and lightweight monitoring and diagnostic device for obtaining ambulatory ECG signals. There is also a need for a device that can be taken home with an ambulatory patient for up to several days, provide sufficient data for therapeutic or diagnostic use by health care personnel, and is sufficiently robust and comfortable for take-home use. There is still a further need for a device that is inexpensive and is hygienic. Moreover, there is a need for a device that provides a variety of set-up and data optimization features while still being user-friendly.